No substitute for simply going and having a look (without cheque book!) at as many as possible.
Don't be shy about asking lots of questions, no matter how dumb you think they are.....and also for advice.
When down a marina have a wonder around for similar boats - if lucky and someone onboard say hello and explain what you are looking at and your low knowledhe base - odds on they will be happy to advise / jump at the chance to show off / talk about their own pride and joy....and things to look out for.
Don't forget that delivery to your chosen berth could be a big factor in your £££ calculations - especially if you need proffesional help and / or some immediate refurb / equipment.....